On Sunday 5 May 2024 at 20:46 UTC, a SYN flood targeted a healthcare portal customer in the Benelux. The attack peaked at 109.6 Gbps and lasted 135 minutes. Traffic originated from 3960 autonomous systems in 33 countries, predominantly mobile carrier ranges.
| Vector | SYN flood |
| Peak | 109.6 Gbps |
| Duration | 135 min |
| Time to mitigation | 0.448 s |
| Attack traffic reaching origin | 0.036% |
| Legitimate traffic challenged | 0.51% |
Timeline
The attack was preceded by a publicly announced sales event. Edge packet filters identified the flood by source port and payload signature and dropped it at line rate across 31 points of presence.
What the customer saw
No customer-visible impact. The on-call engineer was notified and acknowledged the incident from the dashboard.
Recommendations
- Review allow-listed partner ranges quarterly.
- Add a dedicated rate limit for the targeted route.
- Keep origin IPs out of public DNS history.